1. The Field of the Invention
The present invention relates to a method and apparatus providing a guidance system for an underwater observation camera system.
2. Prior Art
In the past, when an observation camera system was required for underwater work below a platform, the usual means of visual contact involved using a ROV (Remote Operated Vehicle). Not only are these submarines very expensive to operate underwater, but they are also fairly delicate machines. This often leads to extended operational downtime of the ROV due to repairs and required maintenance. Another risk that comes with using a ROV for observation below a platform is the possibility of the vehicle becoming entangled in one of the many levels of piping which form the platform jacket structure.
Several years ago it was proposed to use a conventional guideline camera system instead of the usual ROV for observation during a subsea tieback operation (to a platform). The operator (platform owner) had planned to provide a conduit from the platform deck to the subsea wellhead at the mudline by using a pre-installed conductor pipe. The top of the conductor pipe extended to the platform deck above the waterline, but the bottom of the conductor pipe stopped some distance (approximately 50 feet) above the underwater wellhead. A camera system was run inside the pre-installed conductor down to the bottom of the pipe and positioned to observe operations at the wellhead. A significant shortcoming of this design is that the operator was unable to observe at any levels except those below the bottom of the conductor pipe. On deepwater platforms, it is equally important to observe the entry of tools at every guide level in addition to making observation at the wellhead.